Stator for a camshaft adjuster, with a washer for reducing axial bearing play

ABSTRACT

A stator assembly ( 1 ) for a camshaft adjuster ( 2 ), including a stator ( 3 ) the exterior ( 5 ) of which has a toothed portion ( 4 ) for absorbing torque provided by a crankshaft is provided. The stator ( 3 ) includes a wall ( 6 ) which integrally forms the toothed portion ( 4 ) and has an axially running cavity ( 7 ) for receiving a rotor ( 9 ). At least one flange section ( 8 ) of the stator ( 3 ), which protrudes radially inwards, forms an axial stop for the rotor ( 9 ). A spacer disk ( 10 ) which is separate from the stator ( 3 ) and the rotor ( 9 ) is present in the cavity ( 7 ) and sealingly rests on the flange section ( 8 ). A vane-type hydraulic camshaft adjuster which includes a rotor and a stator assembly of the above type is provided.

The present invention relates to a stator assembly for a camshaft adjuster, including a stator which preferably has a toothing on its outside for the purpose of absorbing torque provided by a crankshaft, the stator having a wall which preferably integrally forms the toothing and includes a cavity extending in the axial direction for accommodating a rotor, at least one integrally provided flange section of the stator, which protrudes radially inwardly, directly or indirectly forming an axial stop for the rotor.

BACKGROUND

Stator assemblies of this type are used in camshaft adjusters, which are part of a timing assembly of internal combustion engines. Timing assemblies of this type may include fraction mechanism drives, such as chain and belt drives, for both gasoline and diesel engines. Special camshaft adjusters, in which the stator unit is formed as a single piece from the stator and the cover, are known per se.

Established prior art is known, for example, from DE 10 2010 008 003 A1, in which a cell wheel of a device is described for variably setting the control times of gas exchange valves of an internal combustion engine, which includes a cylindrical peripheral wall. The device furthermore has a drive wheel which is situated on an outer lateral surface of the peripheral wall, a sealing cover, which extends radially inwardly from an inner lateral surface of the peripheral wall, and also has multiple projections, which extend radially inwardly from the inner lateral surface of the peripheral wall and in the axial direction from the sealing cover.

U.S. Pat. No. 6,457,447 B1 furthermore describes a sealing plate in a camshaft adjuster, which, however, abuts both the upper side of the rotor and one side of the stator and is thus in sealing contact with a gear wheel.

In the present prior art, the inner base surface of the stator pot is usually re-machined to meet the high evenness requirements of the axial bearing point. The better the evenness at this point, the more the axial bearing play and thus the leakage may be minimized.

However, processing this surface is complex and, in particular, problematic at the transition between the cover surface and the wall of the stator. Namely, a chamfer or a radius occurs here, due to the special tool geometry. This chamfer or the radius must be provided at the rotor and at the sealing strips, so that the rotor and the stator have a sufficient ease of movement and the adjusting process may be carried out. This inevitably results in a circumferential leakage point on the camshaft adjuster, which, however, should be avoided. A stator assembly should ultimately be provided, which avoids the known disadvantages.

SUMMARY OF THE INVENTION

It is an object of the present invention to eliminate the known disadvantages and to provide an economically manufacturable stator assembly, which, in turn, may be used in a hydraulic camshaft adjuster, a leakage simultaneously being effectively avoided.

Complex, re-machining steps of the stator base surface should be avoided.

In a generic stator assembly, this object is achieved by the fact that a spacing washer, which is separate from the stator and from the rotor, is present in the cavity, for example between the stator and the rotor, and is preferably situated in sealing contact with the flange section.

Due to the additional use of a spacing washer which is joined to the stator pot, a complex processing of the stator base surface may be avoided. The spacing washer makes it possible to provide a minimum axial play.

Advantageous specific embodiments are explained in greater detail below.

It is thus advantageous if the spacing washer has at least one recess which extends from the outside to the interior of the spacing washer and which extends approximately in the direction of the center of the spacing washer, the recess being dimensioned and/or provided to establish a form-locked fit with the stator, the stator having at least one inwardly projecting tab for this purpose. In this way, a relative rotation of the spacing washer, which may also be designed as a sealing disk, with the stator may be prevented by using a form-locked fit. A stator assembly which provides the requirements for a precision use may be created thereby. While the preferred connection of the spacing washer to the stator takes place with the aid of a form-locked fit, force-fitted and/or integral connections have other advantages.

If a plurality of approximately rectangular recesses is evenly distributed over the circumference, preferably if 2, 3, 4, 5, 6, 7 or 8 recesses are present, the anti-rotation protection is ensured to a particular extent.

To improve an elasticity of the spacing washer in the radial direction and/or the axial direction, it is advantageous if a central through-opening is provided in the spacing washer and multiple indentations extending in the axial direction are provided between the central through-opening and the outer circumference of the spacing washer.

It is advantageous if the indentations are designed as pockets and/or through-holes. In the case of through-holes, the weight of the spacing washer is also effectively reduced, while the pockets also have a targeted oil conducting effect if oil is used as the hydraulic medium. Other fluids are also conceivable as the hydraulic medium.

It has turned out to be particularly advantageous if the indentations are provided on the side of the spacing washer facing the flange section and/or the pockets are present on the side of the spacing washer facing away from the flange section.

If at least one nub extending in the axial direction, preferably a plurality of evenly distributed nubs, is/are provided in the indentation, the elasticity of the spacing washer, which may also be designed as a sealing disk, pronounced in the axial direction, may be improved. The spacing washer may be manufactured from metallic material, such as a light metal alloy, but also a steel alloy or a plastic material. In addition to the use of plastic or metal for the spacing washer, rubber has also turned out to be sufficiently resilient.

The sealing effect may be improved if a hydraulic medium conducting hole, such as a bore, is provided in the pocket.

It is also advantageous if each pocket is surrounded by a planarly designed, raised edge of the spacing washer/sealing disk, since this also improves the sealing effect.

The present invention also relates to a vane-type hydraulic camshaft adjuster, which includes a rotor and a stator assembly according to the present invention.

It is also advantageous if the spacing washer has a chamfer or rounding (concavity) on its outside, which is adapted to a chamfer or rounding (concavity) existing between the wall of the stator and the transition area between the wall and the flange section. In this way, a manufacturing-related, circumferential chamfer or a corresponding radius on the stator pot may be accepted without requiring any re-machining The stator pot is the integral combination/one-piece design of the stator wall and the flange section(s) of the stator.

The elastic design of the spacing washer in the radial direction for the purpose of adaptation to the stator contour is also advantageous to ensure a circumferentially high sealing function.

It is also effective if the underside of the spacing washer is provided with an elastic profiling, which adapts to the surface and evenness errors of the stator base surface when an axial force is applied.

It is furthermore possible to implement oil channels in the spacing washer for the purpose of supplying the pressure chambers and the locking unit.

The design of the spacing washer with recesses on the underside of the spacing washer for the purpose of implementing a contact force via the oil pressure and thus a minimum axial play during operation is also advantageous.

In other words, a spacing washer is inserted into the stator pot for the purpose of avoiding a complex re-machining of the stator base surface. Due to the separate processing of the spacing washer or also a large number of spacing washers, for example by machining only the spacing washer(s), i.e., with the aid of grinding, a high accuracy of the evenness or the parallelism of the surface may be achieved.

If this spacing washer, which may also be referred to as the sealing disk, is inserted into the stator pot, the evenness errors of the unprocessed stator base are compensated for. The manufacturing-related chamfer at the stator cover transition is caught by a corresponding chamfer on the spacing washer closest thereto. A sharp-edged edge design between the rotor and stator may furthermore be implemented, which results in fewer internal leaks.

The spacing washer may be provided with an elastic design on its outer diameter by removing material. As a result, the spacing washer adapts to the vane running diameter on the stator pot and forms an optimal seal here. Likewise, the circumferential leakage point on a radial bearing may be sealed. Due to the elastic adaptation of the disk to the stator diameter, more approximate manufacturing tolerances of the two individual parts may be allowed, which minimizes the cost pressure.

To compensate for major surface or evenness errors in the stator base, an elastic, finely structured/profiled disk underside surface may be designed. During assembly, the disk is pressed onto the base surface with the aid of a stamp. The profiling is deformed and optimally adapted in the process to the base surface. Due to the elastic resilience of the base structure, a minimum axial play may be implemented. This has a positive effect on leaks.

One additional option of limiting the axial bearing play is to provide the washer with recesses on its back, which fill with oil during operation and thus press the disk against the rotor.

Oil channels for supplying the pressure chambers or the locking unit may also be implemented via the disk.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is also explained in greater detail below with the aid of a drawing. Different specific embodiments are illustrated.

FIG. 1 shows a longitudinal section of a camshaft adjuster according to the present invention, according to a first specific embodiment;

FIG. 2 shows an insulated spacing washer in a first, simple specific embodiment;

FIG. 3 shows a section of the spacing washer from FIG. 2 along line III;

FIG. 4 shows a perspective view of the spacing washer from FIGS. 2 and 3;

FIG. 5 shows a top view of a second specific embodiment of a spacing washer, including recesses, for the purpose of implementing elastic adaptations to the stator surfaces, which is suitable, in particular, for use in wide rotor vanes;

FIG. 6 shows a view of the spacing washer from FIG. 5, according to a section along line VI from FIG. 5;

FIG. 7 shows a perspective representation of the spacing washer from FIGS. 5 and 6;

FIG. 8 shows a third specific embodiment of a spacing washer according to the present invention, including a profiling on the underside, for the purpose of implementing an elastic adaptation to the stator base surface;

FIG. 9 shows a section of the spacing washer from FIG. 8 along line IX;

FIG. 10 shows a view of the spacing washer from FIGS. 8 and 9, seen from the flange section side;

FIG. 11 shows a fourth specific embodiment of a spacing washer according to the present invention, including recesses on the washer underside and at least one oil-conveying bore for each pocket provided on the disk upper side, for the purpose of pressing the spacing washer axially against the rotor, using the oil pressure, which is also conducive to a minimization of the axial play; and

FIG. 12 shows a section of the spacing washer in the exemplary embodiment from FIG. 11 along line XII in FIG. 11.

DETAILED DESCRIPTION

The figures are only schematic and are used only for the sake of understanding the present invention. Identical elements are provided with identical reference numerals.

FIG. 1 shows a first specific embodiment of a stator assembly 1 for a vane-type, hydraulic camshaft adjuster 2. Stator assembly 1 includes a stator 3, which has a toothing 4 on its outside 5.

Torque is transmitted from a crankshaft to stator 3 via toothing 4, with the aid of a traction mechanism drive, which is not illustrated, such as a chain or belt drive. Toothing 4 is an integral part of wall 6 of stator 3, which is in the form of a stator pot.

Stator 3 has a cavity 7, which extends in the axial direction, flange sections 8 projecting from wall 6 of stator 3 radially inwardly into cavity 7 for the purpose of forming a stop for a rotor 9 and also has a spacing washer 10 connected therebetween. Spacing washer 10 may also be referred to as a sealing disk. Flange sections 8 thus form the base of the stator pot and have a central passage.

The state of contact between rotor 9 and flange sections 8 of stator 3 is also understood to be the intermediate connection of another object.

Spacing washer 10 is situated axially between rotor 9 and stator 3. On its side facing flange sections 8 in the circumferential direction, spacing washer 10 has a chamfer 11, which is adapted to a chamfer 12 of stator 3. The two chamfers 11 and 12 may also be designed as roundings.

Spacing washer 10 is preferably manufactured from plastic and inserted into the stator to minimize the axial play.

FIGS. 2 through 4 show a first specific embodiment of a spacing washer 10 according to the present invention, in a first, particularly simple, design. Four recesses 13 are projectingly provided on the outer circumference, in the direction of a center 14 of sealing disk/spacing washer 10.

FIGS. 5 through 7 show two specific embodiments of a spacing washer 10 according to the present invention, indentations 15 of different sizes being provided in the material of spacing washer 10. Indentations 15 here are designed all over as through-holes 16, not all indentations 15 having to be designed as through-holes 16, but also being able to remain designed as unperforated indentations 15.

Another specific embodiment of a spacing washer is provided in FIGS. 8 through 10, a planar surface being formed on the upper side and an indentation 15, which extends all the way to an edge 17, being formed on the underside, axially projecting/protruding nubs 18, which are distributed evenly in a shared plane, being furthermore present in the interior of indentation 15 in the direction of flange sections 8.

In another modification, another exemplary embodiment is represented in FIGS. 11 and 12, indentations 15 here having the shape of pockets 19 on the upper side of spacing washer 10 facing away from flange sections 8. However, a fluid supply passage is provided, for example as a hydraulic medium conducting hole 20. This hydraulic medium conducting hole 20 ensures a passage of hydraulic medium from the upper side of spacing washer 10 to the underside of spacing washer 10 for the purpose of improving a pressing of spacing washer 10 onto rotor 9.

As a sealing disk, spacing washer 10 forms a seal to the outside, i.e., so that a loss of hydraulic medium from the interior of stator assembly 1, due to leaks, is prevented.

LIST OF REFERENCE NUMERALS

-   1 stator assembly -   2 camshaft adjuster -   3 stator -   4 toothing -   5 outside -   6 wall -   7 cavity -   8 flange section -   9 rotor -   10 spacing washer -   11 chamfer of the spacing washer -   12 chamfer of the stator -   13 recess -   14 center -   15 indentation -   16 through-hole -   17 edge -   18 nub -   19 pocket -   20 fluid supply passage/hydraulic medium conducting hole 

What is claimed is: 1-10. (canceled)
 11. A stator assembly for a camshaft adjuster, the stator assembly comprising: a stator for absorbing torque provided by a crankshaft, the stator having a wall including a cavity extending in an axial direction for the purpose of accommodating a rotor, at least one radially inwardly protruding, integrally provided flange section of the stator forming an axial stop for the rotor; and a spacing washer separate from the stator and from the rotor and located in a cavity between the stator and the rotor.
 12. The stator assembly as recited in claim 11 wherein the spacing washer has at least one recess extending from an outside to an interior of the spacing washer and dimensioned to establish a form-locked fit with the stator.
 13. The stator assembly as recited in claim 12 wherein the at least one recess includes a plurality of rectangular recesses distributed evenly over a circumference of the spacing washer.
 14. The stator assembly as recited in claim 11 wherein the spacing washer has a central through-opening, and multiple indentations extending in the axial direction are present between the central through-opening and the outer circumference of the spacing washer.
 15. The stator assembly as recited in claim 14 wherein the indentations are pockets or through-holes.
 16. The stator assembly as recited in claim 14 wherein the indentations are provided on the side of the spacing washer facing the flange section, or pockets are present on q side of the spacing washer facing away from the flange section.
 17. The stator assembly as recited in claim 14 wherein at least one nub extending in the axial direction is provided in the indentation.
 18. The stator assembly as recited in claim 15 wherein a hydraulic medium conducting hole is provided in the pocket.
 19. The stator assembly as recited in claim 15 wherein each pocket is surrounded by a planarly designed, raised edge of the spacing washer.
 20. A vane-type, hydraulic camshaft adjuster comprising: the rotor and the stator assembly as recited in claim
 11. 